Vulkan: Fix accessing stale FB cached variable. This would happen when we start a query after deleting a Framebuffer. Bug: chromium:1262091 Change-Id: I595360bf55fe1757779669f168c95be802b70da5 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3248142 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>